A vibrational acoustic unit comprises a dynamic force motor, a power take-off spring having one end attached to the dynamic force motor and the other end attached to a fluid filled acoustic resonator. The motor oscillates the entire acoustic resonator so as to excite a resonant mode of the acoustic resonator. A method of delivering power to an acoustic resonator comprises resiliently connecting a motor to the resonator, and driving the motor to oscillate the entire acoustic resonator so as to excite a resonant mode of the acoustic resonator.

A vibratory system for a vibration feeder includes pulse means for generating electrical digital pulse signals. A controller controllably converts the electrical digital pulse signals either into an incrementally increasing or decreasing DC voltage level. At least one vibration block is coupled to the controller for being increased or decreased in its amplitude of vibration in response to the respective incrementally increasing or decreasing DC voltage level generated by the controller. A remotely located additional controller, such as a programmable logic controller, may be coupled to the controller for transmitting electrical digital pulse signals to control the amplitude of vibration.

A drive and drive controller for a vibratory conveyor, wherein the drive comprises a pair of pole pieces offset along a direction of action of the drive, and moveable in the direction of action of the drive when energized by a power signal. Preferably, one of the pole pieces is mounted to a tray portion, and the other to a kinetic balancer portion, of the conveyor. The power signal comprises a series of pulse trains of controllable frequency and duration, whereby the drive unit may be vibrated at a controllable frequency and amplitude so that the vibratory conveyor may be readily tuned to optimal performance. Optionally, the voltage level of the power signal may be reduced by an autotransformer in series with the power signal to independently control the power level.

Mechanical resonance of the vibratory feeder is maintained by minimizing a phase angle difference between substantially sinusoidal drive voltage and current wave forms. The mass flow rate of material being fed is controlled by controlling the electrical power applied to the vibratory feeder compared with a desired electrical power computed from a desired flow rate. The preferred embodiment includes synthesized drive wave forms which are variable in frequency and amplitude in order to maintain the vibratory feeder in mechanical resonance at the desired flow rate. Resonant operation and accurate material flow are accomplished without use of electromechanical vibration sensors and control is accomplished using the magnitude and phase relationships between the applied voltage and current drive wave forms.

An elongate vibratory conveyor for moving products is reciprocated by driving a motor with a cyclical nonuniform motion by supplying power nonuniformly to the motor. The conveyor is reciprocated in opposite lengthwise directions, without any substantial movement of the conveyor normal to the lengthwise direction. Motor control circuitry variably drives the motor automatically in response to feedback from a sensor which senses a motion related to the conveyor motion. The feedback signal is compared to a selected one of a set of predetermined different motion patterns, and the motor is driven by supplying power nonuniformly thereto in accordance with the selected motion pattern. The conveyor system readily enables instantaneous reversibility of the product flow at the same average velocity, and instantaneous variable control for modifying the motion of the conveyor to obtain either different desired average product velocities or the same average product velocity at different conveyor inclinations or reciprocating frequencies, all irrespective of changes in conveyor loading or resistance to slip of the products conveyed. Separate motors driving either the same conveyor or separate conveyors are driven with cyclical nonuniform motions in synchronization by synchronizing their respective power supplies.